Thermoplastic elastomers are rubber-like materials that, unlike conventional vulcanized rubbers, can be processed and recycled like thermoplastic materials. When the thermoplastic elastomer contains a vulcanized rubber, it may also be referred to as a thermoplastic vulcanizate (TPV), defined as a thermoplastic elastomer with a chemically cross-linked rubbery phase, produced by dynamic vulcanization.
Thermoplastic vulcanizates containing butyl or halogenated butyl rubber as the rubber phase and a thermoplastic polyolefin as the plastic or resin phase are known in the art. In order to obtain good processability, the compositions may contain additives including oil, such as mineral oil, and slip agents, such as silicone fluids or fatty amides. While such additives improve processability characteristics, they adversely affect the barrier properties of the thermoplastic vulcanizates. Good barrier properties are important when the thermoplastic vulcanizates are used in contact with foods and beverages, and particularly in pharmaceutical applications.
It is therefore desirable to provide a soft, easily processable thermoplastic vulcanizate with good gas barrier properties for use in pharmaceutical applications, while retaining a high level of cleanliness.